Might I suggest you keep it Simple...as the Thai Evisa requirements are stringent...
As you're from the UK...
Simply enter Thailand Visa EXEMPT which gets you 45 days stamp plus one 30 day extension of stay = 75 days.
Do a simple same day border bounce or possibly visit a neighbor SE Asia country...
On reentry you get another 45 days stamp.
This avoids the needed Booking requirements for Thai tourist visa and the financial statement requirements imposed by the UK Thai Embassy.
You can proceed with applying for the Evisa Tourist Visa...
The choice is yours.
I assume that you hold a passport from the UK ???
Or are with Ukraine passport?
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